(1) Field of the Invention
This invention relates to corona discharging devices, and more particularly relates to ionizing devices in which one side of a high voltage power source is connected to a discharge electrode, usually of pointed disposition, and the other side connected to a conductive member, such as an apertured casing, adjacently spaced with respect to the discharge electrodes to effect emission of ions in the gap therebetween. Where a D.C. high voltage power source is connected to the discharge electrodes, ions of a single polarity are emitted from the pointed electrodes, such configurations being known as electrostatic charging devices, and where the pointed electrodes are coupled to an A.C. power source, ions of both polarities are emitted, the latter construction being termed as a static eliminator or neutralizer because of the ability of the emitted dual polarity ions to combine with particles of opposite charge to effect neutralization thereof. There are a number of ionizers presently available on the market which operate on A.C., D.C. and combinations thereof.
The present invention is especially concerned with the cleaning of the discharge electrodes, particularly emitter points, which have a tendency to accumulate dust and dirt at the tip or edge of said electrodes as a result of the electric field created thereabout. This collection of foreign particulates at the tips of the discharge electrodes reduces ion output not only in the case of D.C. charging devices but also reduces efficiency in the instance of static eliminators as well. Moreover, dirt collected on the points of static neutralizers causes the ion output to become unbalanced whereby the area at which the dual polarity ions are directed tends to become charged rather than electrostatically neutral as a result of an excess emission of ions of one polarity or the other.
(2) Prior Art
While brushes and other auxiliary cleaning devices have been employed in combination with electrostatic ionizing devices to dislodge dirt and dust particles from the surface of articles to which they electrostatically adhered (for example, see U.S. Pat. No. 3,128,492), there have been no disclosures of cleansing mechanisms shown for removal of such particulate materials building up on the points of the ionizers themselves. The accumulation of foreign particles at the tips of the discharge electrodes is especially evident in the case of extended range static eliminators where a stream of air or other gas is blown across the high voltage emitter points contained within a housing whose front surface is enclosed by a grille or screen usually connected to ground. Most ionized air blowers have a plurality of ionizing emitters, usually about twenty pointed members. See U.S. Pat. Nos. 4,092,543 and 4,188,530. In such instances, access to the discharge electrodes located behind the grille or screen has been most difficult and usually required disassembly of the enclosing housing in order to remove the accumulation of dust. The present invention is also applicable for the cleaning of the discharge electrodes of electrostatic ionizers other than those using points, for example those having elongate fine wire systems as electrodes, and emitting devices other than ionized air blowers, i.e. static bars (U.S. Pat. No. 3,443,155) nozzles and air guns (U.S. Pat. No. 3,120,626), charging bars (U.S. Pat. No. 3,137,806) and the like.